Looking the code of updateOnDuplicate looks like we can set an array of fields or a boolean . If we pass a boolean true, the bulkCreate tries to update the primary key field as well, trowing an SequelizeForeignKeyConstraintError SequelizeForeignKeyConstraintError: Cannot delete or update a parent row error.

Code: https://github.com/sequelize/sequelize/blob/66fb6b67a74c107bfaf72304db315bf600c37921/lib/model.js#L2348`